runtime: remove obsolete osArchInit function
The osArchInit function was introduced as a workaround for a Linux kernel bug
that corrupted vector registers on x86 CPUs during signal delivery.
The bug was introduced in Linux 5.2 and fixed in 5.3.15, 5.4.2, and all 5.5 and later kernels.
The fix was also back-ported by major distros.
Change-Id: I59990a7df104843955301c5cb8a547614eba145b
GitHub-Last-Rev:
8425af458bfaad0d64d21ff3f3e0049d186f44ed
GitHub-Pull-Request: golang/go#75246
Reviewed-on: https://go-review.googlesource.com/c/go/+/700555
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Michael Pratt <mpratt@google.com>